Reactance controlled relay



Feb. 21, 1933. p 5 EDWARDS ET AL 1,898,432

REACTANCE CONTROLLED' RELAY Filed Oct. 2, 1929 2f :EJ- E; i:

Patented Feb. 2l, 1933 UNITED STATES PATENT oEFlcE PAUL S. EDWARDS, 0FFORT MEADE, MARYLAND, AND NSTANTIN D. BARBULESCO OF DAYTON, OHIOBEACTANUE CONTROLLED BJl'lIiA'YA Application led October 2, 1989. SerialNo. 396,884.

This invention relates to reactance controlled relays and moreparticularly to means for smoothly operating a mechanical or masterrelay.

Broadly, the invention contemplates the modulation of a current at a'frequency equal or vclose to the proper frequency of vibration of acontacting member so that the closing and opening of a secondary circuitcontrolled by the member takes place for eX- actly the same values ofthe mean energizing current due to the description of the residualmagnetism in the relay. y

An object ofthe invention is to provide means for smooth variation ofthe energizing D. C. current where a relay closes and opens at differentvalues.

Another object of the invention is to provide means to close and open amechanical .or master relay for the same values of the magnetizingcurrent, when this current varies Within small limits around the value-by which the magnet operates.

Other objects of the invention will appear from the followingdescription taken in connection with the drawing, which forms a part ofthe specification, and in which:

Figure 1 comprises a schematic view illustrating the various parts thatgo to make up the present invention, and

Figure 2 is a diagram of a resonance curve.

Referringto the drawing for more specificv details of the invention, 10represents generally a vacuum tube having a filament 11, a grid 12 and aplate 13 evacuated envelope or container 14.

Connected to the input and output circuits of the tube is a low losstank circuit com'- prising a large variable capacitance 15 and a smallinductance'l. The value of this capacity and inductance determine andcontrol the frequency at which the tube oscillates.

Connected to thev filament 10 are high vfrequency choke coils 17 and 18.These are composed of a relatively large number of turns of wire and areconnected respectivel in the grid and plate/circufibof the tube. en inoperation, these choke coils introduce or generate two drivingelectromotive enclosed` within an ground potential, and bypasscondensers 22A and 23 of large value permitting circulation ofv highfrequency currents are connected in the plate circuit.

The frequency is controlled mainly by the value of the condenser l5 andthe inductance 16. The condenser 15 is of large value and hence theinterelectrode capacity of the tube becomes suhstantially negligible ineffect.

Connected in the grid circuit is a grid condenser 24 and a leakresistance 25. The value of the condenser and resistance is so chosenthat the high frequency oscillations generated in the tank circuit willperiodically `charge the condenser up to a certain Value and thendischarge through the leak resistance to the ground. Therefore, thecondenser 24 and the resistance 25 produce a periodic interruption andchoking of the high frequency oscillations.

Connected in the output circuit of the tank is a meter 26 and a relay27. The meter 26 is connected with a pot'entiometric arrangement 28which opposes the current flowing from the filament to the plate batteryand the rela cuit inc uding a batteryv 30 and a device 31. The openingand closing of this relay which operates-at different values is theessence of .the present invention.

Inductivelycoupled to the tank circuit is an exterior circuit comprisinga coupling or loading coil 32 and conductors.33 and 34. This couplingmay be utilized for inducing losses in the tank circuit to increase thefrequency ofthe periodic oscillations and effect a correspondingincrease in the value of the plate current.

at which the tube operates is adapted to close a secondary cirtheapproach of mass close tothe external circuit serve to operate themechanical or master relay. It has been found that, in instances wherethe modulated frequency is very high, the mechanical relay will notclose A and open the secondary value of the plate circuit for the samecurrent. For instance, if the armature has been adjusted, so that therelay closes the contact for a current of two (2) milliamperesy throughits coil, it will not open if the external cause has departed and theplate current has dropped to one point five (1.5) milliamperes.

Thisis objectionable for it decreases the sensitivity of the apparatus.-It may be overcome by using an ultra sensitive relay in place of thesensitive meter connected in the output circuit with the potentiometricar.-

rangement, but this materially increases the cost of production and itis therefore not desirable.

vThe following means has been found extremely simple and effective. Whenthe apparatus has been adjusted, so that the external circuit is inresonance or close to resonance to the tank circuit, the plate circuithas a value'of say one point eight (1.8) milliamperes correspondingtothe ordinate AA, the relay is not aEected. For this situation, we canadjust the frequency of the modulation just below the natural frequencyof vibration of the armature of the mechanical relays. This can beeasily accomplished by proper selection of the grid leak as previouslyexplained.

When mass approaches the external circuit, its capacity increases. Thisincreases the load in the tank and consequently increases the platecurrent to. a greater value BB=2 milliamperes, for which the armature isattracted by the electromagnet and closes the secondary circuit. l

When the plate current increases, the frequency of modulation increasesapproaching the resonant period of vibration of the armature, whichstarts to vibrate violently closing and breaking contact very rapidly. Agreater increase in the plate current due to a closer position `of themass to the external circuit will further increase .the modulatedfrequency and the armature will not be further affected. This insures avery positive contact.

When the mass is removed or withdrawn, the plate current moves down fromCCL-three (3) milliamperes, andas soon as it reaches two (2)milliamperes=BB, the armature starts to vibrate violently due tomechanical resonance, thus overcoming the force due to residualmagnetism in fthe-core and the contact is broken as soon as'the platecurrent comes back to the normal value AA=one point eight (1.8)milliamperes Where there is nothing to affect the external circuit.

I It will thus be seen that if thev current is modulated at a frequencyequal or close to vthe proper frequency of vibrations of the contactingmember, the closing and opening of the secondary circuit will take placefor exactly the same value of the main energizing current ldue to thedestruction of the residual magnetism.

Although this invention has been described in connection with certainspecific embodimentsthe principles involved are susceptible of numerousother applications that will readily occur to' persons skilled in theart. The invention is, therefore, to be limited only as such limitationsare clearly -imposed by the app-endedA claims.

Having thus described the various features of the invention, whatweclaim as new and desire to secure by Letters Patent, is: i

1. A self-modulating high frequency oscillator having means formodulating the lhigh frequency currents in combination with arelapoperated by the output of said voscillator and vibrating at thefrequency corresponding to the frequency of modulation when the outputcurrent is barely suicient to actuate said relay.

2. A lator having means for modulating frequency currents in combinationwith a responsive v' rent from said oscillator and having a natural'mechanical period of vibration of vthe same frequency as the modulatingfrequency self-modulated high frequency oscilwhen the output current isbarely sucient to actuate the device, and means for forming deviceoperated by the output curthe high whose frequency of modulation varieswith j its'intensity, and which means is so regulated that the frequencyof modulation of said current is equal to the natural period ofvibration of the armature when the intensity of the current is equal tothat required to actuv ate the relay and means to vary the intensity ofsaid current.

' 4. In combination, a mechanical relay having an armature with a fixednatural period of vibration and a field requiring a predeter- .minedcurrent to actuate the relay, a selfmodulated high frequency oscillatorhaving means for modulating the high frequency -currents and itsoutput'connected to said relay, said modulating means being soregulated' that the vfrequency of modulation is equal to the naturalperiod of vibration of the armature when the intensity of its outputmemes current is equa io that required actu/ete the reejf, and means tovary the mtemity or the outpiii current.

5i. In combination with e selmcuiae high frequency oscillator havingineens for moduariiig he highffrequency currenis, u, mcchanicai rei-ayconnected in ihe plate cir uuic ofshe osciletor. and having e natu"period of vibration adapte to be actuaftcd by the meen value of theplate current of @511e esciiictor, a secondary circuit controile by cherelay, said means for modulating the high frequency currents adaptec tobe adjusted so as to produce resonance in. the armature of the relay atthe point of closing or breaking the secondary circuit.

r 6. En combination with a seif-mociuiated high frequency oscillator,having means for modulating the high Afrequency currcnw, a reay operableoy electrical variations in u maglie-Liebig element thereof, saidmagueiiizing eiemeii "being comiecteci to 'bhe output ci seidosciiictor, sai means 'for moduiceing the high frequency currentschanging Wib the infbeusiiy of che enero; rig curren for" destrcyio cheresiduali ng 'forces L' the energizing i my euoetciicieiy *fue same e herieb eericy or vibration of the comacimg; e reey wher-i the'imeusiiy o'iig current is esireiy

